Methods1) Heat the oil in a frying pan. Add the onion and garlic and fry for 5 minutes until soft. 2) Add the carrots, pepper, chopped tomatoes, 150 ml of water and the stock cubes. Simmer for 10 minutes.3) Tip in the can of lentils with their juices and then simmer for a further 10 minutes until the carrots are cooked, but not soft.4) Meanwhile, boil the sweet potatoes in a large pan for 15 minutes or until tender. Drain and mash with a little margarine.5) Pour the lentil mixture into an oven-proof dish and top with the sweet potato mash. Sprinkle with the cheese and bake in the oven at 190°C for 25-30 minutes. Serves 4.